Technical Field
This disclosure relates to magnetic resonance imaging (MRI) data sampling methods. More specifically, this disclosure relates to dynamic three-dimensional (3D) contrast-enhanced MR angiography (CE-MRA) and dynamic contrast enhanced (DCE) MRI, including approaches for increasing compatibility with advanced reconstruction algorithms.
Description of Related Art
MRI system can create external magnetic fields. These fields may be able to interact with polarized atoms in an object and generate images from detected induced currents from on-resonance polarized atoms.
CE-MRA and DCE-MRI are two dynamic applications of MRI that can image contrast enhanced signal variations during the time course of contrast agent passing through. They can utilize similar enhancement mechanisms, but can have different goals. CE-MRA can focus on vascular signals where contrast agent concentrations are very high and high spatiotemporal resolution can be critical. DCE-MRI, on the other hand, can focus on tissue signals, where contrast agent concentrations can be lower and change more slowly, and such changes can allow pharmacokinetics to be quantified.
Various sampling and reconstruction techniques have been proposed to address and improve the spatial versus temporal resolution trade-off in CE-MRA and DCE-MRI. Early view-sharing methods, such as keyhole [J. J. van Vaals, M. E. Brummer, W. T. Dixon, H. H. Tuithof, H. Engels, R. C. Nelson, B. M. Gerety, J. L. Chezmar, and J. A. den Boer, “‘Keyhole’ method for accelerating imaging of contrast agent uptake,” J. Magn. Reson. Imaging JMRI, vol. 3, no. 4, pp. 671-675, August 1993] and time-resolved imaging of contrast kinetics (TRICKS) [F. R. Korosec, R. Frayne, T. M. Grist, and C. A. Mistretta, “Time-resolved contrast-enhanced 3D MR angiography,” Magn. Reson. Med., vol. 36, no. 3, pp. 345-351, September 1996], filled the missing data from adjacent time frames. Since non-Cartesian sampling can be more robust to motion and efficient for dynamic imaging, TRICKS was extended to use radial projections [K. K. Vigen, D. C. Peters, T. M. Grist, W. F. Block, and C. A. Mistretta, “Undersampled projection-reconstruction imaging for time-resolved contrast-enhanced imaging,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 43, no. 2, pp. 170-176, February 2000] and spirals [J. Du and M. Bydder, “High-resolution time-resolved contrast-enhanced MR abdominal and pulmonary angiography using a spiral-TRICKS sequence,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 58, no. 3, pp. 631-635, September 2007]. Other non-Cartesian implementations include k-space weighted image contrast (KWIC) [H. K. Song and L. Dougherty, “Dynamic MRI with projection reconstruction and KWIC processing for simultaneous high spatial and temporal resolution,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 52, no. 4, pp. 815-824, October 2004], golden angle stack-of-stars [L. Feng, R. Grimm, K. T. Block, H. Chandarana, S. Kim, J. Xu, L. Axel, D. K. Sodickson, and R. Otazo, “Golden-angle radial sparse parallel MRI: combination of compressed sensing, parallel imaging, and golden-angle radial sampling for fast and flexible dynamic volumetric MRI,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 72, no. 3, pp. 707-717, September 2014], vastly undersampled isotropic projection reconstruction (VIPR) [A. V. Barger, W. F. Block, Y. Toropov, T. M. Grist, and C. A. Mistretta, “Time-resolved contrast-enhanced imaging with isotropic resolution and broad coverage using an undersampled 3D projection trajectory,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 48, no. 2, pp. 297-305, August 2002], highly constrained back projection (HYPR) [C. A. Mistretta, O. Wieben, J. Velikina, W. Block, J. Perry, Y. Wu, K. Johnson, and Y. Wu, “Highly constrained backprojection for time-resolved MRI,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 55, no. 1, pp. 30-40, January 2006], and stack-of-spirals [Y. F. Yen, K. F. Han, B. L. Daniel, S. Heiss, R. L. Birdwell, R. J. Herfkens, A. M. Sawyer-Glover, and G. H. Glover, “Dynamic breast MRI with spiral trajectories: 3D versus 2D,” J. Magn. Reson. Imaging JMRI, vol. 11, no. 4, pp. 351-359, April 2000].
Performance of non-Cartesian sequences can be limited by gradient errors and off-resonance artifacts. For this reason, investigators have reverted to Cartesian sequences where the phase encode (PE) order provides variable density, much like non-Cartesian approaches. Such sequences can include Cartesian projection reconstruction (CAPR) [C. R. Haider, H. H. Hu, N. G. Campeau, J. Huston 3rd, and S. J. Riederer, “3D high temporal and spatial resolution contrast-enhanced MR angiography of the whole brain,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 60, no. 3, pp. 749-760, September 2008], stochastic trajectories (TWIST) [R. P. Lim, M. Shapiro, E. Y. Wang, M. Law, J. S. Babb, L. E. Rueff, J. S. Jacob, S. Kim, R. H. Carson, T. P. Mulholland, G. Laub, and E. M. Hecht, “3D time-resolved MR angiography (MRA) of the carotid arteries with time-resolved imaging with stochastic trajectories: comparison with 3D contrast-enhanced Bolus-Chase MRA and 3D time-of-flight MRA,” AJNR Am. J. Neuroradiol., vol. 29, no. 10, pp. 1847-1854, November 2008], interleaved variable density (IVD) [K. Wang, R. F. Busse, J. H. Holmes, P. J. Beatty, J. H. Brittain, C. J. Francois, S. B. Reeder, J. Du, and F. R. Korosec, “Interleaved variable density sampling with a constrained parallel imaging reconstruction for dynamic contrast-enhanced MR angiography,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 66, no. 2, pp. 428-436, August 2011], a multi-level radial profile ordering [M. Akgakaya, T. A. Basha, R. H. Chan, H. Rayatzadeh, K. V. Kissinger, B. Goddu, L. A. Goepfert, W. J. Manning, and R. Nezafat, “Accelerated contrast-enhanced whole-heart coronary MRI using low-dimensional-structure self-learning and thresholding,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 67, no. 5, pp. 1434-1443, May 2012], differential subsampling with Cartesian ordering (DISCO) [M. Saranathan, D. W. Rettmann, B. A. Hargreaves, S. E. Clarke, and S. S. Vasanawala, “Differential Subsampling with Cartesian Ordering (DISCO): a high spatio-temporal resolution Dixon imaging sequence for multiphasic contrast enhanced abdominal imaging,” J. Magn. Reson. Imaging JMRI, vol. 35, no. 6, pp. 1484-1492, June 2012], variable-density Poisson ellipsoid [R. M. Lebel, J. Jones, J.-C. Ferre, M. Law, and K. S. Nayak, “Highly accelerated dynamic contrast enhanced imaging,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 71, no. 2, pp. 635-644, 2014], and an ordering that gradually improves spatial resolution [N. Gdaniec, H. Eggers, P. Bornert, M. Doneva, and A. Mertins, “Robust abdominal imaging with incomplete breath-holds,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 71, no. 5, pp. 1733-1742, May 2014].
Cartesian and non-Cartesian sequences have also been combined, starting with Time resolved interleaved projection sampling with 3D Cartesian Phase and Slice encoding (TRIPPS) [J. Du, “Contrast-enhanced MR angiography using time resolved interleaved projection sampling with three-dimensional Cartesian phase and slice encoding (TRIPPS),” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 61, no. 4, pp. 918-924, April 2009] that applied rasterized radials on the PE plane, and golden angle radial phase encoding (Golden-RPE) [C. Prieto, S. Uribe, R. Razavi, D. Atkinson, and T. Schaeffter, “3D undersampled golden-radial phase encoding for DCE-MRA using inherently regularized iterative SENSE,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 64, no. 2, pp. 514-526, August 2010] that combined radial sampling and Cartesian readouts. TRIPPS and Golden-RPE were succeeded by golden angle (GA) variants [M. Doneva, C. Stehning, K. Nehrke, and P. Börnert, “Improving Scan Efficiency of Respiratory Gated Imaging Using Compressed Sensing with 3D Cartesian Golden Angle Sampling,” ISMRM, p. 641, 2011], variable-density radial (VDRad) [J. Y. Cheng, M. Uecker, M. T. Alley, S. S. Vasanawala, J. M. Pauly, and M. Lustig, “Free-Breathing Pediatric Imaging with Nonrigid Motion Correction and Parallel Imaging,” ISMRM, p. 312, 2013], and golden angle spiral variants [C. Prieto, M. Doneva, M. Usman, M. Henningsson, G. Greil, T. Schaeffter, and R. M. Botnar, “Highly efficient respiratory motion compensated free-breathing coronary mra using golden-step Cartesian acquisition,” J. Magn. Reson. Imaging JMRI, February 2014].
Most of the aforementioned methods accelerate time-resolved MRI by undersampling in k-space, and use parallel imaging [K. P. Pruessmann, M. Weiger, M. B. Scheidegger, and P. Boesiger, “SENSE: sensitivity encoding for fast MRI,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 42, no. 5, pp. 952-962, November 1999], [M. A. Griswold, P. M. Jakob, R. M. Heidemann, M. Nittka, V. Jellus, J. Wang, B. Kiefer, and A. Haase, “Generalized autocalibrating partially parallel acquisitions (GRAPPA),” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 47, no. 6, pp. 1202-1210, June 2002] and/or compressed sensing [M. Lustig, D. Donoho, and J. M. Pauly, “Sparse MRI: The application of compressed sensing for rapid MR imaging,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 58, no. 6, pp. 1182-1195, December 2007] for reconstruction. Poisson disc sampling [K. S. Nayak and D. G. Nishimura, “Randomized Trajectories for Reduced Aliasing Artifact,” ISMRM, p. 670, 1998] has been a choice for undersampling since compressed sensing was introduced to MRI [M. Lustig, D. Donoho, and J. M. Pauly, “Sparse MRI: The application of compressed sensing for rapid MR imaging,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 58, no. 6, pp. 1182-1195, December 2007]. Numerous algorithms have been proposed to efficiently generate Poisson disc sampling patterns, including dart throwing [M. A. Z. Dippé and E. H. Wold, “Antialiasing Through Stochastic Sampling,” in Proceedings of the 12th Annual Conference on Computer Graphics and Interactive Techniques, New York, N.Y., USA, 1985, pp. 69-78], jittered sampling [R. L. Cook, “Stochastic Sampling in Computer Graphics,” ACM Trans Graph, vol. 5, no. 1, pp. 51-72, January 1986], best candidate [D. P. Mitchell, “Spectrally Optimal Sampling for Distribution Ray Tracing,” in Proceedings of the 18th Annual Conference on Computer Graphics and Interactive Techniques, New York, N.Y., USA, 1991, pp. 157-164], and more recent O(N) boundary sampling [D. Dunbar and G. Humphreys, “A Spatial Data Structure for Fast Poisson-disk Sample Generation,” in ACM SIGGRAPH 2006 Papers, New York, N.Y., USA, 2006, pp. 503-508] and modified dart throwing [R. Bridson, “Fast Poisson Disk Sampling in Arbitrary Dimensions,” in ACM SIGGRAPH 2007 Sketches, New York, N.Y., USA, 2007].
Lebel et al. [R. M. Lebel, J. Jones, J.-C. Ferre, M. Law, and K. S. Nayak, “Highly accelerated dynamic contrast enhanced imaging,” Magn. Reson. Med. Off. J. Soc. Magn. Reson. Med. Soc. Magn. Reson. Med., vol. 71, no. 2, pp. 635-644, 2014] proposed Poisson ellipsoid sampling based on dart-throwing for dynamic imaging by extending the 2D Poisson disc pattern to 3D ky-kz-t space. This method can provide excellent transform sparsity, can be compatible with parallel imaging, and can limit temporal redundancy. Unfortunately, it can be computationally intensive, have many input variables, and be poorly suited to variable temporal resolution.
In contrast, golden angle Cartesian sampling [M. Doneva, C. Stehning, K. Nehrke, and P. Börnert, “Improving Scan Efficiency of Respiratory Gated Imaging Using Compressed Sensing with 3D Cartesian Golden Angle Sampling,” ISMRM, p. 641, 2011] can provide more coherent sampling than the Poisson ellipsoid approach. Yet, it can allow flexibility in the specification of temporal resolution during reconstruction and fast on-line generation of the PE order. Here PD is denoted to variable density Poisson ellipsoid sampling and GA is denoted to Cartesian golden angle radial sampling.
Previous approaches may not effectively produce sampling patterns that satisfy all of the following properties: efficient, robust to gradient errors and off-resonance artifacts, excellent transform sparsity, compatible with parallel imaging, flexible in the specification of temporal resolution during reconstruction, and fast on-line generation.